Trail Running > Routes > Brecon Beacons Routes > Waun Fach & the Dragon’s Back
An 11.5 km trail run to the highest peak in the Black Mountains and a thrilling descent on the spine of the Dragon’s Back.
Why run this trail?
At 811 m, Waun Fach is the highest point in the Black Mountains and the third highest summit in the Brecon Beacons. Unsurprisingly, it’s a popular destination for hikers and runners all year round.
This particular route is something of a classic – mapped, photographed, blogged and vlogged in countless corners of the internet. It’s also one of the quickest, most accessible ways to the top and includes two memorable landmarks: the serrated ridge of Y Grib (the “Dragon’s Back”) and the atmospheric ruins of Castell Dinas, perched on a grassy mound in the Rhiangoll Valley.
This trail run follows the circuit in an anti-clockwise direction, saving the Dragon’s Back for the descent. Plummeting down its spine with incredible views on all sides is a thrill not to be missed.
Dinas Castle Inn to Rhiw Trumau
The trail begins behind the car park at Dinas Castle Inn, Pengenffordd (parking £5 via honesty box or pay in the pub). I arrived at lunchtime on a grey Saturday in late September and waited 15 mins for a spot to become available.
An initial section on a woodland path emerges onto a small farm road for about a kilometre. It then picks up a short section of green lane before rising steeply onto the Rhiw Trumau – a broad track cut into the hillside that offers nice views down into the Rhiangoll Valley and the isolated mountain of Mynydd Troed.
The gradient eases as the path opens out onto moorland, eventually reaching a small cairn where several tracks converge. This is a good place to get your bearings and take in the surrounding peaks: Mynydd Llysiau (663 m) directly to the right and the craggy outcrop of Pen Trumau (707 m) on the left – the start of the climb towards the summit of Waun Fach.
Pen Trumau to Waun Fach
The small, exposed plateau of Pen Trumau is reached via a grassy track through the heather and a final steep scramble to its rocky top. This afforded me the first far-reaching mountain views of the run: the shapely silhouette of Pen Allt-mawr at the southern end of the Black Mountains and even the faint pyramid of Sugar Loaf through the gloom. Blasts of cutting mountain wind had me quickly on the move again.
The path to Waun Fach is well trodden. Alternating between gravel and paved sections, it’s not the most exciting running, but it does avoid a schlep over rough, bleak moorland to reach the summit.
The summit, as it happens, is an underwhelming, boggy plateau that gave me flashbacks to The Cheviot earlier in the year. it’s marked with an almost apologetic smattering of stones – possibly the result of somebody emptying their pockets at the top. Oh well.
The Dragon’s Back (Y Grib) and Castell Dinas
From the summit of Waun Fach, it’s an easy run north on an obvious track towards the descent of Y Grib. The views of the Rhiangoll Valley open out once more and, passing Pen y Manllwyn (not really discernible as a peak in its own right) the track narrows and veers left to hit the descent.
The Dragon’s Back truly is the gift that keeps on giving (or the descent that keeps on… descending?) – a rollercoaster that plunges almost continuously to scrub off about 400 metres of altitude over its three kilometre length. It’s perfectly pitched and features breathtaking views that shift at every turn.
It’s important to ignore any side paths that fork left and right off the main ridge. Stay dead centre all the way down the descent – you definitely don’t want to be backtracking uphill again to correct any mistakes and miss all the fun.
At the bottom, the route provides a sting in its tail – a nasty little climb up to the ruined ramparts of Castell Dinas. With my legs burning from the descent, I cursed this final assault on my dignity and blitzed what was left of it to bring the run to a close.
Tapping out the final few hundred metres across small fields back to the car park, I reflected on the run. Waun Fach’s summit? Atmospheric but definitely not beautiful. The shoulders of the mountain, however, were far more comely.
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Disclaimer
All routes and GPX files are provided as a guide only. Conditions, rights of way, and landmarks may change. Always carry an up‑to‑date map and use your own judgement. See the Trail Run Disclaimer page for details.